1. Field of the Invention
The present invention relates generally to centrifuges and more specifically to a solid bowl centrifuge with liquid release during rotation which does not require the solid bowl centrifuge to cease rotation to drain the liquid portion.
2. Discussion of the Prior Art
There are numerous designs of centrifuges disclosed in the art such as solid bowl and screen bowl. The centrifuges are used to separate the solid portion from the liquid portion in a slurry. Some of the solid bowl centrifuges include U.S. Pat. Nos. 5,328,441 and 5,733,238 to Carr. Some of the screen bowl centrifuges with side evacuation of liquid portions include U.S. Pat. No. 3,410,479 to Nilson and U.S. Pat. No. 3,986,663. Both the solid bowl and screen bowl centrifuges have drawbacks to their use. A solid bowl centrifuge is typically stopped to drain the separated liquid portion. Screen bowl centrifuges are relatively complex devices. However, it appears that neither design of centrifuge has been found suitable for use in the aggregate industry.
Accordingly, there is a clearly felt need in the art for a solid bowl centrifuge which is less complex than a screen bowl centrifuge, yet allows the liquid to be drained while the solid bowl is in rotation and provides ease of solids removal.
The present invention provides a solid bowl centrifuge which allows liquid to drain while the solid bowl is in rotation. The solid bowl centrifuge with liquid release during rotation includes a frame, solid bowl, drive device, scraper assembly, slurry spray unit, liquid collection trough, and speed control circuit. The solid bowl includes a centrifuge chamber, and a liquid evacuation chamber disposed below the centrifuge chamber. A drive shaft is formed through an axis of the solid bowl. A plurality of openings are formed through the wall of the liquid evacuation chamber. Preferably, the drive shaft is pivotally constrained by the frame on each end thereof.
The scraper assembly includes at least one scraper device and an actuation device. The scraper device includes a scraper blade at least two scraper arms, an actuation arm, and a pivot rod. One end of each of the scraper arms is attached to the pivot rod and the other end is attached to the scraper blade. One end of the actuation arm is attached to the pivot rod and the other end is pivotally attached to the actuation device.
Preferably, a tubular post extends upward from a bottom of the frame and around the drive shaft. The pivot rod is pivotally attached to the tubular post. The slurry spray unit is disposed on the inside of the centrifuge chamber. The liquid collection trough is disposed around and under the liquid evacuation chamber. The drive device causes the drive shaft to rotate. The speed control circuit controls the speed of the drive device.
The solid bowl centrifuge with liquid release during rotation preferably operates in the following manner. Preferably, a predetermined amount of slurry is sprayed on the wall of the centrifuge chamber while rotating. The solid bowl is rotated for a period of time. Next, the speed of the solid bowl is reduced to allow liquid to drain from the centrifuge chamber. The liquid whips around an opening in a partition between the centrifuge chamber and liquid evacuation chamber. The liquid continues to the wall of the liquid evacuation chamber and through a plurality of openings formed in the wall. The liquid is collected in the liquid collection trough and drained therefrom. Next, the speed of the solid bowl is further reduced and the scraper assembly is activated to remove the solid material from the wall of the centrifuge chamber. The solid portion falls out of the centrifuge chamber on to a conveyor or the like. After the solid portion is removed from the wall of the centrifuge chamber, the speed of the solid bowl is increased and the process is repeated.
Accordingly, it is an object of the present invention to provide a solid bowl centrifuge which is less complex than a screen bowl centrifuge.
It is a further object of the present invention to provide a solid bowl centrifuge which allows liquid to be drained while the solid bowl is in rotation.
Finally, it is another object of the present invention to provide a solid bowl centrifuge which provides ease of solids removal.
These and additional objects, advantages, features and benefits of the present invention will become apparent from the following specification.